itemize 环境的项目突出到左边距（scrbook）

Question

我将以下习语与方程链联系起来。我使用环境对齐方程align，标记读者可能不清楚其原理的每个方程。我在这个方程链后面加上一个itemize环境，其中每个方程\item都为其中一个标记方程提供了依据。我使用相应的标签而不是项目符号。下面是一个例子。

\documentclass{scrbook}
\usepackage{amsmath,amsthm}
\newtheorem{theorem}{Theorem}[chapter]
\numberwithin{equation}{theorem}
\begin{document}
\chapter{A Chapter}
\section{A Section}
\begin{theorem}
$2 = 1 + 1$
\end{theorem}
\begin{proof}
\begin{align}
2 &= 2 + 0\label{eq:1}\\
&= 1 + 1\label{eq:2}
\end{align}
where
\begin{itemize}
\item[\eqref{eq:1}] is by Hinkel's lemma, and
\item[\eqref{eq:2}] is by the Fundamental Theorem of Small Integers.
\end{itemize}
\end{proof}
\end{document}

可以看出，用作环境“项目符号”的标签itemize突出到左边距。我该如何纠正这个问题，以便所有内容都呈现在边距之间？

Answer 1

您可以使用labelingKOMA-Script 类提供的环境。

例子：

\documentclass{scrbook}
\usepackage{amsmath,amsthm}
\newtheorem{theorem}{Theorem}[chapter]
\numberwithin{equation}{theorem}
\begin{document}
\chapter{A Chapter}
\section{A Section}
\begin{theorem}
$2 = 1 + 1$
\end{theorem}
\begin{proof}
\begin{align}
2 &= 2 + 0\label{eq:1}\\
&= 1 + 1\label{eq:2}
\end{align}
where
\begin{labeling}{\eqref{eq:2}}% syntax: \begin{labeling}{<widest label>}
\item[\eqref{eq:1}] is by Hinkel's lemma, and
\item[\eqref{eq:2}] is by the Fundamental Theorem of Small Integers.
\end{labeling}
\end{proof}
\end{document}

或者第二项有更多文字：

如果项目只有一行，您也可以使用：

\documentclass{scrbook}
\usepackage{blindtext}% only for dummy text
\usepackage{amsmath,amsthm}
\newtheorem{theorem}{Theorem}[chapter]
\numberwithin{equation}{theorem}
\begin{document}
\chapter{A Chapter}
\section{A Section}
\begin{theorem}
$2 = 1 + 1$
\end{theorem}
\begin{proof}
\begin{align}
2 &= 2 + 0\label{eq:1}\\
&= 1 + 1\label{eq:2}
\end{align}
where
\begin{labeling}{}
\item[\eqref{eq:1}] is by Hinkel's lemma, and
\item[\eqref{eq:2}] is by the Fundamental Theorem of Small Integers. \blindtext
\end{labeling}
\end{proof}
\end{document}

与上述结果唯一的区别是项目可能的第二行的缩进：

Answer 2

使用以下enumitem包：

（红线表示文本边框）

\documentclass{scrbook}
\usepackage{amsmath,amsthm}
\newtheorem{theorem}{Theorem}[chapter]
\numberwithin{equation}{theorem}
\usepackage{enumitem}

\begin{document}
\chapter{A Chapter}
\section{A Section}
\begin{theorem}
$2 = 1 + 1$
\end{theorem}
\begin{proof}
\begin{align}
2 &= 2 + 0\label{eq:1}\\
&= 1 + 1\label{eq:2}
\end{align}
where
\begin{itemize}[wide]
\item[\eqref{eq:1}] is by Hinkel's lemma, and
\item[\eqref{eq:2}] is by the Fundamental Theorem of Small Integers.
\end{itemize}
\end{proof}
\end{document}

Answer 3

如果你喜欢自己动手使用 LaTeX，或者你不会/不能使用scrextend或enuitem其他包来格式化列表，那么有一个简单的解决方案\leftmargini（注意最后我因为仅适用于列表的第一级）必须手动添加或考虑标签宽度。

另一种方法是使用原始list环境而不是itemize，这样也可以自动生成方程引用。请注意，在这种情况下，修改后的是\leftmargin（没有最后的“i”）。关于列表的好处是您可以在自己的简单环境中进行转换。示例：

\documentclass{scrbook}
\def\a{is by Hinkel's lemma, and} % one line dummy ext
\def\b{is by the Fundamental Theorem  % two lines dummy ext
of Small Integers. Lore ipsum dolor sit amet and bla bla bla...} 
% \usepackage[showframe]{geometry}  % uncomment to show margins ...
\parindent0pt  % Disclaimer: To lazy to set lenghts in LaTeX mode, sorry. 
               % You should use \setlengths or you will have nightmares.

\newcounter{eq}
\newlength\eqlab
\settowidth\eqlab{\eqref{eq:2}}
\newenvironment{equation-references}{ 
\begin{list}{\eqref{eq:\arabic{eq}}}{\usecounter{eq}
\labelwidth2\eqlab
\labelsep1em 
\leftmargin\dimexpr\labelwidth+\labelsep}
}{\end{list}}

\usepackage{amsmath}
\newtheorem{theorem}{Theorem}[chapter]
\numberwithin{equation}{theorem}

\begin{document}
\chapter{A Chapter}
\section{A Section}
\begin{theorem} $2 = 1 + 1$ \end{theorem}
\begin{align} 2 &= 2 + 0\label{eq:1}\\&= 1 + 1\label{eq:2} \end{align}

Set \verb|\leftmargini| manually to have label in margin:

{\leftmargini3.3em
\begin{itemize} \item[\eqref{eq:1}] \a \item[\eqref{eq:2}] \b \end{itemize}}

Or with some indentation:

{\leftmargini4em
\begin{itemize} \item[\eqref{eq:1}] \a \item[\eqref{eq:2}] \b \end{itemize}}

With automatic identation according to label width:

{\leftmargini\dimexpr\leftmargini+\eqlab
\begin{itemize} \item[\eqref{eq:1}] \a \item[\eqref{eq:2}] \b \end{itemize}}

Making a simple list autonumbered:

\begin{list}{\eqref{eq:\arabic{eq}}}{\usecounter{eq}}
\item \a \item \b \end{list}

Custom \verb|equation-references| environment with some label indentation:

\begin{equation-references}
\item \a \item \b 
\end{equation-references}

\end{document}